The invention relates generally to power-driven conveyors and, more particularly, to switch conveyors including conveyor belts with selectively rotatable rollers useful in diverting conveyed articles to selected positions across the width of the belt.
In a typical beverage industry application, cans or bottles are sequentially filled in a filler, warmed in a warmer, packaged in a case packer, and loaded onto a pallet by a palletizer. Multiple palletizers are often used so as not to bottleneck any of the upstream processes, such as the filler. Shoe sorters are often positioned just before the palletizers to distribute conveyed cases of filled cans or bottles among lateral belt positions leading to individual outfeed conveyors each transporting the cases to one of the palletizers according to the palletizers"" availability.
One typical shoe sorter includes an endless conveyor belt or chain constructed of a series of slats flanked by drive chains. A shoe for pushing articles across the conveyor belt is movably attached to each slat. Typically, the shoe either surrounds the slat, top to bottom and front to back, or has an appendage that extends through a transverse slot formed through the slat from top to bottom. A guide track arrangement in the conveyor frame beneath the conveyor belt guides the shoes across the belt as the belt is driven in the conveying direction. The specific arrangement of the guide track programs the system to push conveyed articles to specified lateral positions on the conveyor belt.
But these chain-driven slat conveyors have shortcomings. One is that their construction limits the placement of connecting joints between consecutive slats because of interference with the shoes and associated appendages. For that reason, the slats can sag in the middle because they are supported mainly at the drive chains positioned out of the shoe""s travel range at the side edges of the slats. This problem is especially noticeable on wider conveyors. Another shortcoming is that the shoe mechanisms and the guide track arrangement can be complex and, consequently, expensive.
Roller conveyors are also used as shoe sorters in many applications, especially for heavy articles, such as tires, and also for beverage cases and for low-profile, multi-sized articles, such as packages and mail. But one of the problems with roller conveyors is that these metal conveyors can be noisy, especially as their bearings wear. Frequent maintenance operations, such as lubricating and tightening, and repairs are a way of life with roller conveyors.
Thus, there is a need for a conveyor that can divert conveyed articles, such as cases and packages, but without the shortcomings of shoe sorters or roller conveyors.
These needs and others are satisfied by a switch conveyor embodying features of the invention. One version of the conveyor includes a conveyor belt with rollers arranged in first and second lanes. A plurality of parallel longitudinal bearing surfaces underlies the conveyor belt along a belt carryway. The bearing surfaces are selectably moveable into and out of contact with the bottom side of the belt and the first and second lanes of rollers along the carryway. The conveyor belt, which extends in width from a left side to a right side and in thickness from a top side to a bottom side, runs longitudinally in a direction of belt travel along the carryway. A plurality of first rollers is arranged to rotate about first axes disposed at a first angle relative to the direction of belt travel. The first rollers are arranged to define the parallel longitudinal first lanes. Similarly, a plurality of second rollers is arranged to rotate about second axes disposed at a different second angle. The second rollers define the second lanes. The first and second lanes alternate across the width of the belt.
Another version of the switch conveyor includes a modular conveyor belt with rollers and a switch mechanism. The modular conveyor belt is constructed of a series of rows of belt modules connected end to end at hinges. At least some of the rows include rollers that can extend above and below top and bottom sides of the belt. First and second groups of the rollers can rotate about axes generally in different first and second directions. The first group of rollers is arranged in spaced apart longitudinal first lanes, and the second group, in spaced apart longitudinal second lanes. The switch mechanism, which underlies the belt along a carryway portion of the conveyor, is selectably adjustable between contact with the first group of rollers at the bottom side of the belt under the first lanes and contact with the second group of rollers in the second lanes. As the switch mechanism selectably contacts the first or second groups of rollers, it causes the selected group to rotate as the conveyor belt advances along the carryway.
In a third version of the switch conveyor, a conveyor mat is divided across its width into a plurality of longitudinal lanes of rollers. All the rollers in each lane rotate about parallel axes. The rollers of adjacent lanes rotate about non-parallel axes. A switch mechanism underlies a carryway portion of the conveyor and is adjustable between lanes to rotate the rollers of alternately selectable lanes.